An oxygen mask is read as a need for space and recovery. The airline rule of putting on your own mask first is often echoed here: look after yourself before others.
When this appeared in your dream, what were you feeling?
My Cosmic Code has a private dream journal. Write a dream down and the app picks out the symbols in it, shows what dream books say about them and, over time, which words recur across your entries. The journal is stored on your device only.